Regeneration of unsupported vanadium sulfide catalyst

ABSTRACT

A carbonized, unsupported nonstoichiometric vanadium sulfide catalyst is regenerated by way of a three-stage treatment at elevated temperatures. In the first stage, carbon is removed from the catalyst by contacting with elemental sulfur at an elevated temperature in the range of about 500* to about 1,000* C. The substantially carbon-free catalyst is treated with a mineral acid, or anhydrous HF, to dissolve metallic contaminants, and further treated in a third stage with elemental sulfur at a temperature in the range of 300* to about 500* C. to form vanadium tetrasulfide.

nited States Patent Gatsis [451 Jan. 18, 1972 [54] REGENERATION OFUNSUPPORTED VANADIUM SULFIDE CATALYST [72] Inventor: John G. Gatsis, DesPlaines, Ill.

[73] Assignee: Universal Oil Products Company, Des

Plaines, 111.

[22] Filed: Feb. 2, 1970 21 Appl. No.: 8,057

[52] U.S. C1. ..252/415, 23/23, 23/29 V, 23/134, 23/138, 208/144,208/213, 208/264,

[51] Int. Cl. ..B0lj 11/76, BOlj 11/02 [58] Field ofSearch..252/4l1,413,415;208/264,

[56] References Cited UNITED STATES PATENTS 2,038,599 4/1936 Piereta lW,....,,..,..gs 1 34 Archibald 2,370,707 3/1945 252/411 R 2,709,639 5/1955Folkins et a1. 252/411 8 3,161,585 12/1964 Gleim et a1. ...208/2643,165,463 1/ 1965 Gleim et a1. ..208/264 Primary Examiner-Daniel E.Wyman Assistant Examiner-P. E. Konopka Attomey-James R. Hoatson, Jr. andRobert W. Erickson [57] ABSTRACT.

5 Claims, No Drawings APPLICABILITY OF INVENTION The invention describedherein encompasses a procedure for catalyst regeneration. The catalyticcomposites, to which my invention is specifically directed, are themetallic sulfides of the metals of group V of the periodic table.Furthermore, the metallic sulfide catalysts are unsupported, which termis intended to designate a catalyst, or catalytic component which is notan integral part of a composite with a refractory inorganic oxidecarrier material. The regeneration procedure is particularly adaptableto the sulfides of the metals of group V, and especially vanadium.

The carbonized sulfides of the foregoing metals are those which havebeen employed in the slurry processing of asphaltene-containinghydrocarbonaceous material. This hydrocarbonaceous material, includingatmospheric tower bottoms, vacuum tower bottoms, crude oil residuals,topped crude oils, coal oil extracts, crude oils extracted from tarsands, etc., are generally categorized in the art as black oils.

Black oils contain high molecular weight sulfurous compounds inexceedingly large quantities. In addition, they contain excessivequantities of nitrogenous compounds, high molecular weightorganometallic complexes principally comprising nickel and vanadium, andasphaltenic material. The asphaltenic material is generally found to becomplexed with, or linked to sulfur, and, to a certain extent, with theorganometallic contaminants. An abundant supply of suchhydrocarbonaceous material exists, most of which have a gravity lessthan 200 API, and which is further characterized by a boiling rangeindicating that 10.0 percent by volume, and generally more has a normalboiling point of a temperature of about l,050 F.

Difficulties encountered in processing black oils, utilizing a fixed bedof a supported catalyst, have indicated that a more advantageous routeis a slurry process wherein an unsupported catalytic component isadmixed with the charge stock. The principal difficulty with a fixed bedsystem is the lack of a technique which affords the catalytic compositessulfur stability in the presence of the asphaltenic and organometalliccompounds. Not only does the catalyst deactivate rapidly, as a result ofthe formation of carbon, but the metallic contaminants become depositedupon the catalysts employed, steadily increasing in quantity until suchtime as the composition of the catalytic composite is changed to theextent that undesirable results are obtained. The asphaltenic fractionconsists primarily of high molecular weight, nondistillable cokeprecursors, insoluble in light hydrocarbons such as propane, pentane, orheptane.

The primary purpose of the present invention is to provide an efficientand economical scheme for the regeneration of the carbonized,unsupported catalysts utilized in the slurry processing ofhydrocarbonaceous black oils. As hereinbefore set forth, my invention isparticularly directed toward the regeneration of an unsupportednonstoichiometric vanadium sulfide catalyst.

OBJECTS AND EMBODIMENTS A principal object of my invention is to providea method for the regeneration of a carbonized, unsupported catalyst. Acorollary objective is to regenerate a carbonized, unsupported vanadiumsulfide catalyst.

Another object of my invention is to afford a regeneration procedurewhich removes deposited metallic contaminants, from the charge stock,from a carbonized, unsupported vanadium sulfide catalyst.

Therefore, in one embodiment, my invention encompasses a method forregenerating a carbonized, metal-contaminated vanadium sulfide catalystwhich comprises the steps of:

a. removing carbon from the vanadium sulfide catalyst;

b. treating the decarbonized catalyst with a mineral acid or anhydrousHF, thereby dissolving the metallic contaminants; and,

c. treating the vanadium catalyst with elemental sulfur at a temperaturein the range of about 300 C. to about 500 C. to form vanadiumtetrasulfide.

Other objects and embodiments of my invention, relating to particularregeneration conditions and techniques will become apparent from thefollowing detailed summary of the invention.

SUMMARY OF INVENTION Previous investigations into the slurry processingof hydrocarbonaceous black oils have indicated that the preferredunsupported catalytic component is a vanadium sulfide onnonstoichiometric sulfur content. Through the use of the termunsupported, it is intended to designate a catalyst, or catalyticcomponent which is not an integral part of a composite with a refractoryinorganic oxide carrier material. That is, the catalyst is a vanadiumsulfide without the addition thereto of extraneous material. Althoughthe precise atomic ratio of sulfur to vanadium is not known withaccuracy, X-ray analyses have indicated that the nonstoichiometric,catalytic sulfide has a ratio of sulfur to vanadium not less than 0.821,nor greater than 1.8:1. This is not intended to mean that the vanadiumsulfide has but a single specific sulfur/vanadium atomic ratio, butrather refers to a mixture of vanadium sulfides having nonstoichiometricsulfur/vanadium atomic ratios within the aforesaid range. Although fouroxidation states are known for vanadium, 2, 3, 4 and 5, Periodic Tableof the Elements, E. H. Sargent & Company, 1964, only threestoichiometric vanadium sulfides are sufficiently stable foridentification. These are: monovanadium sulfide, VS; sesquivanadiumsulfide, V 5 and, pentavanadium sulfide, V 8 Handbook of Chemistry andPhysics, Chemical Rubber Publishing Company, 42nd Edition, Pg. 680,19604961. The literature is replete with references to many identifiablenonstoichiometric vanadium sulfides which are specific compounds intheir own right, possibly the most common being the tetrasulfide, VS Ithas previously been found that the catalytic vanadium sulfide is notidentifiable as any of the stoichiometric vanadium sulfides, nor as V8,.The catalytic, nonstoichiometric vanadium sulfide is, however, producedin the reaction zone in situ by the conversion of the tetrasulfide atreaction conditions.

The slurry-type conversion process is generally effected by comminglingthe charge stock/vanadium sulfide slurry with hydrogen in an amount offrom about 5,000 to about 100,000 s.c.f./bbl. The hydrogen streamgenerally contains from 1.0 mol percent to about 20.0 mol percent ofhydrogen sulfide. The slurry is introduced into a reaction zone, theinlet temperature generally being controlled at a minimal level of about225 C., and at higher levels to the extent that the outlet temperaturedoes not exceed about 500 C. The reaction chamber is generallymaintained under an imposed pressure greater than about 500 p.s.i.g.,and preferably at a level of from 1,500 to about 5,000 p.s.l.g. Oneparticularly preferred technique is to introduce the slurry mixture intoa lower portion of the reaction zone. This has the advantage that theextremely heavy portion of the charge stock will have an appreciablylonger residence time within the reaction zone, with the result that agreater degree of conversion is attainable.

The reaction product efiluent is subjected to a series of separationsteps which result in an asphaltenic sludge containing carbonizedvanadium sulfide having metallic impurities either deposited thereon, oragglomerated therewith. Since the sludge will contain distillablehydrocarbon products, it is treated, for example, by a series offiltration and solvent washing techniques. Suitable solvents includemethyl naphthalene, carbon tetrachloride, benzene, toluene, etc. Carbon,coke and other carbonaceous material is removed from the catalyst bybeing admixed with elemental sulfur and heated to a temperature of about500 C. to about l,000 C., whereby carbon disulfide is formed and removedfrom the metal components in the vaporous state. When the metals aresubstantially free from the coke and other carbonaceous material, thetemperature is lowered to a level within the range of from about toabout 100 C. At the lower temperature level, the metallic components aretreated with a mineral acid such as sulfuric acid, hydrochloric acid, orhydrofluoric acid, or anhydrous HF. The vanadium sulfides, includingV8,, V 8 V 8 VS and the nonstoichiometric vanadium sulfides areresistant to such acids, whereas the metallic contaminants, whether asmetals, sulfides or oxides will react with the acids to form volatile orwater-soluble compounds. In addition to nickel, such other metalliccontaminants include copper, lead, iron, magnesium, etc., and may existas metal oxides, for example, silica or alumina, or as sulfides such asiron sulfide. Although there is no indication that these substances, inrelatively minor amounts, are detrimental to the catalyst, they willcontinue to accumulate as the catalytic vanadium sulfide is recycled andeventually overpower the catalytic action. The acid-treated catalyst issubjected to a series of washing steps to remove traces of the acid,after which the metal components are dried.

in order to ensure that the vanadium exists in the sulfide form whichconverts to the nonstoichiometric catalytic vanadium sulfide within thereaction zone the dry component is treated with elemental sulfur,preferably in an atmosphere of hydrogen sulfide and/or carbon disulfideat a temperature in a range of about 250 C. to about 500 C. Traces ofelemental sulfur are readily removed from the sulfide component throughthe use of carbon disulfide.

I claim as my invention:

1. A process for regenerating a carbonized, metal-contaminatedunsupported vanadium sulfide catalyst which comprises the steps of:

a. removing carbon from the vanadium sulfide catalyst by heating incontact with elemental sulfur;

b. treating the decarbonized catalyst with a mineral acid or anhydrousHF, and dissolving metallic contaminants; and,

c. treating the vanadium catalyst with elemental sulfur at a temperaturein the range of 300 C. to about 500 C. to form vanadium tetrasulfide.

2. The process of claim 1 further characterized in that said mineralacid is sulfuric acid.

3. The process of claim 1 further characterized in that said mineralacid is hydrochloric acid.

4. The process of claim 1 further characterized in that said mineralacid is hydrofluoric acid.

5. The process of claim 1 further characterized in that said catalyst isdecarbonized by heating in contact with elemental sulfur at atemperature in the range of 700 C. to about 1,000 C.

2. The process of claim 1 further characterized in that said mineralacid is sulfuric acid.
 3. The process of claim 1 further characterizedin that said mineral acid is hydrochloric acid.
 4. The process of claim1 further characterized in that said mineral acid is hydrofluoric acid.5. The process of claim 1 further characterized in that said catalyst isdecarbonized by heating in contact with elemental sulfur at atemperature in the range of 700* C. to about 1,000* C.